fix(types):prune unused and ToParts trait

* do not emit unused types. Sometimes though, rustc doesn't seem to
  detect that attributses are actually used
* ToParts trait is used and implemented only when needed.

Linters are back to 'normal'.

Fixes #35

gen/youtube3/src/cmn.rs

@@ -50,6 +50,11 @@ pub trait NestedType: MarkerTrait {}
 pub trait ReadSeek: Seek + Read {}
 impl<T: Seek + Read> ReadSeek for T {}
 
+/// A trait for all types that can convert themselves into a *parts* string
+pub trait ToParts {
+    fn to_parts(&self) -> String;
+}
+
 
 /// A utility type which can decode a server response that indicates error
 #[derive(Deserialize)]
@@ -98,7 +103,10 @@ pub trait Delegate {
     /// Called whenever a server response could not be decoded from json.
     /// It's for informational purposes only, the caller will return with an error
     /// accordingly.
-    fn response_json_decode_error(&mut self, json_encoded_value: &str) {}
+    /// # Arguments
+    /// `&str` - The json-encoded value which failed to decode.
+    /// `Error` - The decoder error
+    fn response_json_decode_error(&mut self, _: &str, _: &serde::json::Error) {}
 
     /// Called whenever the http request returns with a non-success status code.
     /// This can involve authentication issues, or anything else that very much 

src/mako/lib.rs.mako

@@ -6,7 +6,8 @@
 <%  
     from util import (new_context, rust_comment, rust_doc_comment, rust_module_doc_comment, 
                       rb_type, hub_type, mangle_ident, hub_type_params_s, hub_type_bounds, 
-                      rb_type_params_s, find_fattest_resource, HUB_TYPE_PARAMETERS, METHODS_RESOURCE)
+                      rb_type_params_s, find_fattest_resource, HUB_TYPE_PARAMETERS, METHODS_RESOURCE,
+                      UNUSED_TYPE_MARKER, schema_markers)
 
     c = new_context(schemas, resources, context.get('methods'))
     hub_type = hub_type(c.schemas, util.canonical_name())
@@ -21,9 +22,8 @@
 <%block filter="rust_module_doc_comment">\
 ${lib.docs(c)}
 </%block>
-#![feature(core,io, old_io)]
-// DEBUG !! TODO: Remove this
-#![allow(dead_code, deprecated)]
+#![feature(core,io,thread_sleep)]
+// Unused attributes happen thanks to defined, but unused structures
 // We don't warn about this, as depending on the API, some data structures or facilities are never used.
 // Instead of pre-determining this, we just disable the lint. It's manually tuned to not have any 
 // unused imports in fully featured APIs. Same with unused_mut ... .
@@ -49,9 +49,9 @@ use std::marker::PhantomData;
 use serde::json;
 use std::io;
 use std::fs;
-use std::old_io::timer::sleep;
+use std::thread::sleep;
 
-pub use cmn::{MultiPartReader, MethodInfo, Result, CallBuilder, Hub, ReadSeek, Part, ResponseResult, RequestValue, NestedType, Delegate, DefaultDelegate, UnusedType};
+pub use cmn::{MultiPartReader, ToParts, MethodInfo, Result, CallBuilder, Hub, ReadSeek, Part, ResponseResult, RequestValue, NestedType, Delegate, DefaultDelegate};
 
 
 // ##############
@@ -119,7 +119,9 @@ impl<'a, ${', '.join(HUB_TYPE_PARAMETERS)}> ${hub_type}${ht_params}
 // SCHEMAS ###
 // ##########
 % for s in c.schemas.values():
+% if UNUSED_TYPE_MARKER not in schema_markers(s, c, transitive=True):
 ${schema.new(s, c)}
+% endif
 % endfor
 % endif
 

src/mako/lib/mbuild.mako

@@ -747,7 +747,10 @@ if enable_resource_parsing \
                         res.read_to_string(&mut json_response).unwrap();
                         match json::from_str(&json_response) {
                             Ok(decoded) => (res, decoded),
-                            Err(err) => return Result::JsonDecodeError(err),
+                            Err(err) => {
+                                dlg.response_json_decode_error(&json_response, &err);
+                                return Result::JsonDecodeError(err);
+                            }
                         }
                     }\
                     % if supports_download:

src/mako/lib/schema.mako

@@ -2,7 +2,7 @@
     from util import (schema_markers, rust_doc_comment, mangle_ident, to_rust_type, put_and, 
                       IO_TYPES, activity_split, enclose_in, REQUEST_MARKER_TRAIT, mb_type, indent_all_but_first_by,
                       NESTED_TYPE_SUFFIX, RESPONSE_MARKER_TRAIT, split_camelcase_s, METHODS_RESOURCE, unique_type_name, 
-                      PART_MARKER_TRAIT, canonical_type_name)
+                      PART_MARKER_TRAIT, canonical_type_name, TO_PARTS_MARKER, UNUSED_TYPE_MARKER)
 
     default_traits = ('RustcEncodable', 'Clone', 'Default')
 %>\
@@ -27,7 +27,7 @@ ${struct}(${to_rust_type(schemas, s.id, NESTED_TYPE_SUFFIX, s, allow_optionals=a
 <% 
     et = unique_type_name(s.id)
     variant_type = lambda p: canonical_type_name(p.type_value)
-%>
+%>\
 pub enum ${et} {
 % for p in s.variant.map:
     ${p.get('description', 'no description provided') | rust_doc_comment, indent_all_but_first_by(1)}
@@ -73,7 +73,7 @@ ${struct};
         allow_optionals = False
     # use optionals only when needed
     
-    ## waiting for Default: https://github.com/rust-lang/rustc-serialize/issues/71
+    # waiting for Default: https://github.com/rust-lang/rustc-serialize/issues/71
     if s.type == 'any':
         traits.remove('Default')
 
@@ -105,11 +105,13 @@ impl Default for ${s_type} {
 % endif ## type == ?
 
 % for marker_trait in nt_markers:
+% if marker_trait not in (TO_PARTS_MARKER, UNUSED_TYPE_MARKER):
 impl ${marker_trait} for ${s_type} {}
+% endif
 % endfor
 
-% if REQUEST_MARKER_TRAIT in nt_markers and 'properties' in s:
-impl ${s_type} {
+% if TO_PARTS_MARKER in nt_markers and allow_optionals:
+impl ${TO_PARTS_MARKER} for ${s_type} {
     /// Return a comma separated list of members that are currently set, i.e. for which `self.member.is_some()`.
     /// The produced string is suitable for use as a parts list that indicates the parts you are sending, and/or
     /// the parts you want to see in the server response.

src/mako/lib/util.py

@@ -71,6 +71,8 @@
 NESTED_MARKER_TRAIT = 'NestedType'
 REQUEST_VALUE_PROPERTY_NAME = 'request'
 DELEGATE_PROPERTY_NAME = 'delegate'
+TO_PARTS_MARKER = 'ToParts'
+UNUSED_TYPE_MARKER = 'UnusedType'
 
 PROTOCOL_TYPE_INFO = {
     'simple' : {
@@ -365,39 +367,48 @@ def activity_input_type(schemas, p):
 def is_pod_property(p):
     return 'format' in p or p.get('type','') == 'boolean'
 
+
+def _traverse_schema_ids(s, c):
+    ids = [s.id]
+    used_by = s.used_by + s.parents
+
+    seen = set() # protect against loops, just to be sure ... 
+    while used_by:
+        id = used_by.pop()
+        if id in seen:
+            continue
+        seen.add(id)
+        ids.append(id)
+
+        oid = c.schemas[id]
+        used_by.extend(oid.used_by)
+        used_by.extend(oid.parents)
+    # end gather usages
+    return ids
+
 # Return sorted type names of all markers applicable to the given schema
 # This list is transitive. Thus, if the schema is used as child of someone with a trait, it 
 # inherits this trait
 def schema_markers(s, c, transitive=True):
     res = set()
-    ids = [s.id]
-
-    if transitive:
-        used_by = s.used_by + s.parents
-
-        seen = set() # protect against loops, just to be sure ... 
-        while used_by:
-            id = used_by.pop()
-            if id in seen:
-                continue
-            seen.add(id)
-            ids.append(id)
-
-            oid = c.schemas[id]
-            used_by.extend(oid.used_by)
-            used_by.extend(oid.parents)
-        # end gather usages
-    # end is transitive
+    ids = transitive and _traverse_schema_ids(s, c) or [s.id]
 
+    has_activity = False
     for sid in ids:
         activities = c.sta_map.get(sid, dict())
         if len(activities) == 0:
             continue
+        has_activity = True
         # it should have at least one activity that matches it's type to qualify for the Resource trait
         for fqan, iot in activities.iteritems():
             _, resource, _ = activity_split(fqan)
             if resource and activity_name_to_type_name(resource).lower() == sid.lower():
                 res.add('cmn::%s' % RESOURCE_MARKER_TRAIT)
+            m = c.fqan_map[fqan]
+            params, _ = build_all_params(c, m)
+            part_prop, _ = parts_from_params(params)
+            if part_prop is not None and 'properties' in s:
+                res.add(TO_PARTS_MARKER)
             if IO_RESPONSE in iot:
                 res.add(RESPONSE_MARKER_TRAIT)
             if IO_REQUEST in iot:
@@ -412,8 +423,8 @@ def schema_markers(s, c, transitive=True):
     if len(c.sta_map.get(s.id, dict())) == 0:
         res.add(PART_MARKER_TRAIT)
 
-    if len(res) == 1 and PART_MARKER_TRAIT in res and len(s.used_by) == 0:
-        res.add('UnusedType')
+    if not has_activity:
+        res.add(UNUSED_TYPE_MARKER)
 
     return sorted(res)
 

src/rust/cmn.rs

@@ -48,6 +48,11 @@ pub trait NestedType: MarkerTrait {}
 pub trait ReadSeek: Seek + Read {}
 impl<T: Seek + Read> ReadSeek for T {}
 
+/// A trait for all types that can convert themselves into a *parts* string
+pub trait ToParts {
+    fn to_parts(&self) -> String;
+}
+
 
 /// A utility type which can decode a server response that indicates error
 #[derive(Deserialize)]
@@ -96,7 +101,10 @@ pub trait Delegate {
     /// Called whenever a server response could not be decoded from json.
     /// It's for informational purposes only, the caller will return with an error
     /// accordingly.
-    fn response_json_decode_error(&mut self, json_encoded_value: &str) {}
+    /// # Arguments
+    /// `&str` - The json-encoded value which failed to decode.
+    /// `Error` - The decoder error
+    fn response_json_decode_error(&mut self, _: &str, _: &serde::json::Error) {}
 
     /// Called whenever the http request returns with a non-success status code.
     /// This can involve authentication issues, or anything else that very much